External defibrillators are electronic devices that can be used to automatically diagnose and treat patients with particular cardiac problems. External defibrillators typically treat patients through defibrillation, which is a process that delivers an electrical discharge to a patient's heart to stop cardiac arrhythmias. The defibrillation can allow the patient's heart to reestablish an effective rhythm.
Many cardiac conditions that are treatable by external defibrillators can lead to death or serious injury (e.g., brain damage) within minutes of the onset of symptoms if defibrillation is not delivered to the patient. The patient's chances for avoiding death or permanent injury increase as the time between the onset of symptoms and defibrillation treatment decreases. In some cases, the survival rate of patients suffering from cardiac arrhythmia decreases by about 10% for each minute the administration of treatment is delayed, and the survival rate of some patients can be less than 2% after about 10 minutes without treatment.
Some patients have medical conditions that make the patients especially susceptible to needing defibrillation treatment. For example, patients that have recently suffered a heart attack or undergone a heart procedure, such as bypass surgery, may have a higher risk for a life-threatening arrhythmia. Those patients may benefit from the use of a wearable defibrillator. A wearable defibrillator includes a garment that can be worn beneath the patient's clothing. The wearable defibrillator also includes a monitor-defibrillator that constantly monitors the patient's heart for life-threatening heart rhythms and automatically delivers defibrillation treatment to the patient's heart if a life-threatening heart rhythm is detected.
In order to take most advantage of a wearable defibrillator, the components of a wearable defibrillator need to be effective for the time that the patient wears the wearable defibrillator. Making a wearable defibrillator comfortable for the patient to wear and usable for the length of time that the patient wears the wearable defibrillator increases the likelihood that the patient will be wearing the wearable defibrillator when an arrhythmia develops and that the patient will receive effective treatment for the arrhythmia.